Most people have their own list of cliche plot devices that they hate, or at least dislike. Here's mine.
This basic plot element has been used in approximately a million movies. Be it indians, samurais, dragons, elves or other types of historically based or fantastical creatures, they are the last of their kind, the sole survivors of a once-powerful group of people or creatures who, for one reason or another, have come to the brink of extinction. Sometimes there's only one individual left, the very last of his kind. (It's almost always a he. In many cases by the end of the movie he will find that he was not the last one, but that there was a female as well. In rare cases a small community.)
This kind of "the last of the dying race" is not only overly used as a plot device, it's also usually boring. I'm tired of seeing the struggles of these last individuals. What I would like to see is that group of people or creatures on the height of their civilization. That would be cool.
One of the most common reasons why this group is on the brink of extinction is:
This is an even more common and overly used cliche: Science, technology and progress is represented by greedy colonialists and unscrupulous individuals or companies who desire nothing else than to conquer and harvest natural resources for their own gain, completely disregarding any inhabitants of the natural ecosystem. They are like swarms of locusts, consuming and destroying everything in their path, with complete disregard about the consequences.
This is contrasted with the natives, who are "one with nature", who have grown in and learned to respect their environment, who contribute to their environment more than they consume. In many cases the environment and the nature is given some kind of (at least implied) supernatural aspect, as if it was sentient or had some kind of supernatural "energy" (that the colonialists don't understand at all).
At its core, the basic message of this overly used plot device is "pollution and destruction of natural resources is bad, don't do it". I know that. I don't need nor want to be constantly reminded of that. If I want to see the effects of pollution and overuse of natural resources, I can watch documentaries and read articles on the subject. When I watch a movie, I want to go away from reality for a moment, I don't want to be constantly reminded of it.
The other annoying thing is that science and progress is always depicted as a negative thing in these movies. I like a lot more movies and TV series where technology and progress is depicted as neutral or even a positive thing (such as in Star Trek).
Nature is often given (rather ironically) supernatural aspects, which often leads to:
Whenever a character in a movie shows healthy scepticism about something, be it an impending natural disaster, the intents of the antagonists, a seemingly supernatural or uncommon phenomenon, ufos, etc, he is always wrong. In most cases this sceptic will die from the very thing he doubted.
This is especially jarring with the supernatural phenomena. For some reasons movies have always wanted to draw people (especially kids) away from healthy scepticism. The message is always that scepticism is wrong and has negative (even fatal) consequences.
For once I would like to see a big blockbuster movie where the sceptic is actually right and the protagonists fall into shame for believing nonsense.
A combination of this and the "progress bad, nature good" plot device also often presents:
Movies should promote science, not give a picture of science as being evil, unnatural, destructive and selfish. The occasional mad scientists is ok, but depicting science and scientists as generally evil is way too common. This is especially common when they are contrasted in many movies with the natives who live in a natural environment.
Another common plot device where this cliche is overused is when humanity encounters non-human intelligent (and sometimes even non-intelligent) life. The reaction is to always capture them against their will, run horrendous lab experiments, and so on. Scientists are always depicted as unscrupulous and heartless individuals who couldn't give a damn about what their test subjects feel.
In comic books superheros must protect their identities at all costs, lest their enemies take revenge by attacking their loved ones and families. Being involuntarily unmasked, their real identity being revealed, is usually one of the most catastrophic things that a comic book hero could suffer.
This same principle doesn't seem to apply to superhero movies, for some strange reason. In the comics Spiderman being unmasked caused disastrous havoc and suffering. In the movies it had no consequences whatsoever (not even when he unmasked in front of his enemies). In the comics it was explored (as a dream sequence) what would happen if the secret identify of the Iron Man would be revealed, and the consequences were once again catastrophic. In the movies no drastic consequences to speak of. Batman? No problem in unmasking himself in front of an enemy in movies.
Judge Dredd is quite noteworthy in that his face has never been shown in the comics (even though in-story characters sometimes have seen it). In the movie? You guessed it.
Especially the Spiderman movies have been really egregious and cringeworthy about this, and I really hate that aspect of them.
There has probably been no superhero movie sequel (it usually happens only in a sequel, very rarely on the first movie) where the superhero in question hasn't temporarily lost his superpowers in one form or another. Superman? Check. Spiderman? Check. X-Men? Check (although at least in this case it kind of follows a big story arc in the comics, but anyways). The list goes on.
I find this plot device boring, unimaginative and definitely overused. (And no, I don't find this plot device any more enticing in the comics either.)
In some cases the action is voluntary. The reason to relinquish the superpowers is always completely stupid.
If two characters of opposite sex show awakening affection to each other, there will become a point in the movie where they will slowly try their first kiss... only to be interrupted at the last second before it happens. Especially prevalent in comedies, but used basically in all genres.
This cliche is so overused that you can see this coming from a mile away, which is annoying and breaks willing suspension of disbelief.
In more modern movies this gets sometimes subverted (in other words, no interruptions), but the moment still gets ruined because you expect it to be interrupted, which detracts from the movie. The thousands of previous movies using this annoying cliche have ruined any movies which subvert it.
A character might be suffering from some kind of illness, injury or other type of calamity (either just a generic illness or injury, or something relevant to the plot of the movie), but he hides it and claims that nothing is wrong if asked. Usually there's absolutely no reason whatsoever for this character to do that. In many cases it's not something that the character would have to be ashamed of or shunned by others if he told them. In fact, in many cases it's just outright stupidity because it's something that others could help with. I have never understood what the big idea is.
This has been seen in about a million movies, and it pops up all the time. For some reason screenwriters never get tired of this cliche.
Ninjas (who were available for contract jobs as spies and assassins, although the vast majority of their jobs were way more mundane) really existed in real life. That's not a myth. However, they never, ever dressed in black (or blue or whatever) outfits with masks. Not during night missions, not during anything. Wearing such an outfit would have been equivalent to carrying a neon sign saying "I'm an assassin spy, kill me now".
Likewise they never carried any obvious weapons, concealed or otherwise, during their secret missions. No katanas, no sharpened shurikens (which actually might not have historically existed at all), nothing like that. Carrying concealed weapons would have also been tantamount to carrying a sign saying "I'm a dangerous assassin, execute me now".
The most common outfit for a real-life ninja on a secret mission was that of a peasant, farmer or wandering salesman (usually of farming or construction tools). They had weapons alright, but not obvious weapons. They used farming and construction tools as their weapons. They needed to pass routine inspections by enemy guards and samurais with flying colors. If a ninja ever used eg. an actual katana on a mission, it would have been taken from a fallen enemy samurai during combat (and probably discarded afterwards, if the ninja needed to go under cover once more).
The myth of black-hooded ninjas was most probably born from kabuki theater. (This is also where the more egregious myths are also probably from, for example that ninjas could turn invisible and fly.) It was a convention of the medium in the past that stagehands, who helped with practical special effects (such as flying objects etc.) would dress in all-black (with only the eyes visible), and that they really "were not there". The audience was expected to exercise some willing suspension of disbelief and ignore the stagehands for the sake of entertainment, and accept that these black-wearing stagehands were not there in-story. Thus "invisibility" of a character (such as a ninja) could be "achieved" by making it wear like a stagehand. To an audience who was routinely accustomed to ignore the black-wearing stagehands it would have been a big surprise if one of them was actually a character (and eg. suddenly killed one of the normal characters).